Shutter for motion picture projection machines



Jan. 26, 1932. o. A` ROSS 1,843,093

SHUTTER FOR MOTION PICTURE PROJECTION MACHINES Filed Feb. 19, 1926 C-..L E LLM fig@ Fig? Fig@ figg L47/ @5T wo i EA 56T' l \\467/ l L57/ M456W'- E 49F 52x 514 55\\\ /l/ 59 ,I Flglo i f4@ Q1 w3 i Patented Jan.26, 1932 PATENT OFFICE OSCAR A. ROSS, OF YORK, N. Y.

SHUTTER FOR MOTION PICTURE PROJECTION MACHINES Application filedFebruary 19, 1996. Serial No. 89,363.

This invention relates to shutters, and more Aparticularly to that classof shutters employed on motion picture projection machines. l

' Known shutters for *motion picture projec tion ,machines produce atime interval, or

period during which the image, or scene on the lilm is projected ontothe screen, or

mirror on a stage,` and a period, or time intei-val of darkness, duringwhich no image,

or scene is projected onto said screen, or mii ror. The period duringwhich the scene, or image is projected, is generally slightly longerthan that of the period of darkness.

Assume the interior of any motion picture theater and that a scene ofsubstantially high illuminative density per unit area, is beingprojected on a screen by a known type of motion picture projectionmachine, and

'= is being viewed by a spectator, who may be one of an audiencenumbering one thousand,

v more or less, persons and that said machine has held the iilmstationary for a suliicient length of time to permit all the functioningmembers of said spectators eye to assume normal adjustment for the/scenebeing projected. The said adjustments will be subf stantially asfollows; the pupils of the eye will dilate or contract to adjust for theintensity of the illumination before the eye,

the lenses will flatten, or thicken to adjust for the distance at whichsight is focused, the retina will adjust for the varied density andoutlines of the scene projected whereby said l scene may be transmittedto the brain, or

Y through the lens, the lensv will in attempting to penetrate thedistance of the darkness and the retina be affected to record darknessto the brain.

Assume that the scene oi high illuminative density per unit areahasagain appeared, perhaps in slightly perceptible altered form. The saidspectators eyes are afrain called upon for readjustment of thefunctioning members to substantially the adjustment for the formerperiod of high illuminative density per unit area. y

The hereintofore related sequences f adjustments of the functioninglmembers of spectators eyes is what occur in a more or less minutedegree in the eyes of every spectator in the audience of a movinlOpicture theater. Furthermore the rapidity with which the periods ofprojected scenes and subsequent darkness occur, produces, not only agreat strain on the muscles of the eyes, but also a great strain on thenervous system controlling the said muscles, as, said system is ofinvoluntary action controlled by the sub-conscious mind.

The retina of the eyes are also strained for the reason that the mind ofthe spectator is absorbed in the progressive movement of the imageprojected on the screen, and, due to the persistence of thought governedby the progression of said image, the brain does not become cognizant ofthe interval of darkness although it has been impressed upon said retinaand probably wholly, or partially transmitted to the said brain.

The complaint of tired eyes after having attended a movie is common andit is believed is seriously lowering the standard of eyesight ofsubstantially all participants of motion picture theaters.

One object of this invention is to produce a shutter, which whenoperated in conjunction with known motion picture projection machines,will relieve the aforesaid eye strains to as great a degree as ispossible with the peculiar construction of said machines, and,comprehends means for producing the same intensity of illumination perunit area during the dark period as is produced during the image orscene" period of projection of a movie film, in this manner not callingfor a change of adjustment of either the pupils, or lenses, or, on thepart of the retina, calling for a distinction of light intensity.

Although the strain on the retina is thereby greatly reduced, it is notentirely eliminated as the high lights and shadows of a scene projectedon a movie screen, affect different portions of the retina, whereasduring the dark period produced by the applicants improved shutter, thefield, although of the same intensity of illumination, is flat havingsubstantially no high lights, or shadows, in

-' other words the intensity of illumination is uiiiform over the entirearea` projected upon the screen. ,j

j Another object of this invention to produce a shutter for motionpicture projection machines wherein means are furnished to prevent unduestrains on the projection apparatus if. stopped suddenly,y such strainsbcing: caused by' thestoredv kinetic energy inherent in a rapidlyrevolving motion picture shutters leaving substantial weight.

Another, object is to produce a more e'Hicient and economical devi-ce ofthe kind described.l

Other-objectsraml advantages will appear as the description of theinvention pro- 1. ing from the spirit of the invention or sacrificingany of its details.

En describing the invention in detail, reference is had to theaccompanying drawings, wherein I have-illustrated one embodiment ofmyinvention, and,vwherein like characters of reference designatecorresponding parts throughout the several views, and in which A iFigure 1,. is-.an elevational view of a preferred form of the improvedshutter, and Fig. 2, is a sectional view of the same taken online A-A1of Fig.v 1, a id Fig. 3, is a modified form of shutter shown in section,and, Fig. 4, is a plan view of a section of movie film represented inintervals of time and effects when employed with known shutters,andfFig. 5, is a similar view when employed witlrthe applicants improvedshutter, and, Figs.4 6., 7- and 8,` areY diagrammatic views illustratingrefraction of projected light rays, obtained by the applicants improvedshutter, and, Figs. 9, 10 and 11, are sectional views,- enlarged, ofcertain portions of shutter blades which may be employed inthe appli- V'n 6* cants 'improved shutter.

Referring to Figs. 1 and 2, hub 1, comprises' a split tubular extension2, adapted, by screws 33, to clamp in known manner sleeve 4, and saidhub, to the motion picture machine shaft, not shown, also a flange 5,having projections G-G, adapted to impinge on one side of shuttersupport 7, also a tubular extension 8, secured to which is collar 9,receiving impingement of one end of spring 10, the other end 'of saidspring acting to force friction zlate 11, againstthe opposite side ofshutter support 7. Friction plate 11, is restrained from turning onextension 8 by key 14 rigidly secured thereto, the upper portion of saidkey being arranged slidably in key-way 14 of member 8, said member alsohaving convex projections 12--12, adapted to seat in concave recesses13-13, of shutter support 7.

Secured to shutter support 7, by screws 15--15, and annularl member 16,are shutter blades 172-17, preferably of mouldedtransparent materialhaving a tongue 18, adapted to mate with groove 19in said shuttersupport, said blades being further located and secured by the channelring 29, composed of stamped annular rings 20 20, secured together withrivetsQO'a, or spot welding. Said ring may be more firmly located bywires 21-21, one end of .which is secured to screws 15-15, and the otherdrawn through said ring and suitably secured to the periphery thereof,as for example by soldering. A suitable resilient packing as 22--22, maybe enrployed to obtain uniform juncture of the parts. After assembly thecomplete shutter may be mechanicallyv balanced by the addition of aweight, as 23, placed in the channel of ring 20-20- Referring to Fig. 3,the shutter support 7, of Figs. 1 and 2', has been modified to the formshown by member 25, of Fig. 3, and to which are secured shutter blades17-17, mem ber 26, suitably secured to member 25 serving to secure saidshutter blades to said member-l and form a composite structure which maybe removably secured to hub 27, by screws E28- 28.

Shutter blades 17-17 are preferably composed of a transparent material,as for cxample glass, and the surfaces thereof are prismatic instructure, said prisms being small in area, as compared to the totalarea of the beam of light projected by a motion picture projectionmachine atthe point where it is intercepted by said shutter blades. Theangularity of the refracting surfaces of said prisms is preferably suchthat the refracted rays of light do not fall outside the area ofillumination ordinarily projected on a-movie screen when the projectedbeam is not intercepted by the' shutter blade and as will be hereinaftermore fully described.

Referring to Fig. 4,' the distan between the lines B and C, represent,in intervals of time, the movement of two complete cycles of movie filmexposure employing well known shutters; The exposure during the timeinterval 30, is a scene. composed of a high light,vor backgroundsubstantially white in color,'the object 35, as for example a mountain,is Vgray in color.y The composite density of illumination projected onthe screen is very high,and is equal to the result obtained if a colorscreen of very light gray, or brown, wereinterposed inthe path of thebeam of light projected by the particular motionpicture projectionmachine in use, it being` considered that no film, other than the colorscreen, aforesaid, is present. The eyes of a spectator viewing saidexposure, will, heretofore related, tend to adjust themselves to thehigh density of illumination projected onto the screen.

l The exposure during time interval 31, the period during which a bladeof a known shutter. is interrupting the projected beam of light, andduring which the movement of film is'` taking place, is substantiallyblack, or dark, and the intensity of illumination projected onto thescreen is nil, and is equivalent to placing an opaque screen in the pathof the projected beam of light from said projection machine. The eyes ofsaid spectator, are now called upon to readjust for this abnormal changein density of illumination.

At the lapse of time interval 31, the film exposure represented by timeinterval 32 appears,substantially of the same high density ofillumination as the time interval 30, The eyes of said spectator areyagain called upon to make an abnormaladjustm-ent of the eye functioningmembers to meet this new condition, and, at the lapse of time interval32,

another abnormal change is required to adjust forv the substantially nildensity of illuinination during thetime interval 33.

Referring to Fig. 5, the distance between lines D and E, represent, inintervals of time, the movement ofv two complete cycles of movie filmexposure projected by a motion picture projection machine equipped withthe applicants improved shutter. The exposure during time interval 36,has a density of illumination projected on the screen substantially thesame as time interval 30, of Fig. 4. The succeeding time interval 37,representing the period of'time, during which the shutter blade, as 17,of the yapplicants improved shutter, is interposed between the screenand the projected `beam of light coming through the film, and duringwhich period said film is being moved to the next scene, has a densityof illumina-tiqn projected onto the screen substantiallythe same as theaverage density of illumination during time interval 36, however thedensity is substantially uniform over `the entire field of exposure onsaid screen. y For this reason the eye functioning members controllingthe pupils andj'lenses of 'the spectators eyes,-are not called upon forchange, and the only change called for by the functioning members of theretina, is relocation of high lights and shadows, however, as thepersistence of vision and mind is engrossed in the progression of theimage portrayed on these-reen, no mental cognizance is taken of thisretinal change.

At the lapse of time interval 37, the exposure represented by timeintervall 38 appears, also of substantially the same light density asthat of interval 37, and, as the per.- sistence of mind and vision areabsorbed .in the progression of the movie picture, no change in the eyefunctioning members occurs. The exposure during time intervals 33 and39, are substantially the same as those of 3G and 37.

It will be apparent, that, irrespective of the predominance of the highor low lights exhibited by a frame, the light density during a frameexposure will be followed by an exposure of light of the same densitypassing through the shutter blade except at points on the film where acomplete change ofscene, or title ensues.

It will be further apparent that motion picture projection machinesequipped with the applicants improved shutter will reduce the strains ofthe functioning members of spectators eyes very materially, and it maybe said reduces the strains on the entire physical constitution for thereason that medical experts consider that any strain on the nerves ofthe human system tends to decrease the useful .period of life and alsohastens death.

`Referring to Figs. 6, 7 and 8 which are to be considered as viewingeither vertical or horizontal planes of selected projected fractionalbeams oflight, the rays of which portray portions of a scene appearingon a movie film to be projected on the screen 45 after passing throughthe shutter blade 17. The distance X, representing the distance betweenthe shutter blade 17 and the screen 45, is, for the purpose ofillustration made very short, also, and for the same reason, the widthand depth of the beam at its source, the projector 44, are shown oflarge dimension as compared to the area projected on screen 45.

Fig. 6, as an example, is assumed to be a top view taken on a horizontalplane at substantially the top of the projected light beam. Suitableprismatic surfaces of known construction, and as illustrated in Figs. 9,10 and 11, and any one, of which may be present ou blades 17, at theselected locations through which beams v46, 47, 43 and 49 pass, willrefract the particular fractional beams of projected light,substantially as shown. The exterior beams 46 and 47 will be consideredas of low light intensity, ytherebyproducing al low density ofillumination on screen 45. The rays 48 and 49 will beconsidered to be ofhigh light intensity thereby producing an area 'of highk density of'illumination on said screen. The fbeams 46 and 47 would ordina.- rily.pass to the adjacent sides, or edges of screen45, however, 'with theshutter blade 1T, interposed there between, they not only pass tov the;adjacent center of said screen, but also cross to the opposite sidesthereof. The beams 48. and 49 which Vwould ordinarily have beenprojectedto the adjacent center, are refracted by blade 17, and.projected .to ltl1ead jacenty edge of said screen.

Referring to Fig. 7, which .it is assumed represents'a location, 4alsoin a horizontal plane, and', slightly 'below that illustrated in Fig. 6,thedistaneebeing a small fraction of the. entire distance across theltwo parallel sides of the beam, the two outside beams `:50 Iand 51.,are ref-racted by shutter bladell'? to project said beams `totheadjacent center of screen 45, without crossing. The inside beams5'2-a11d53,'are refracted to pass tothe adjacent edges -of said'screenwithout crossing. Further assuming that the light intensity ofthe lastvnamed beams to be relatively opposite to that of the ybeams shown inFig. 6, the beams of light projected to the adjacent center lof screen45 will produce a low. density of illumination, whereas the beamsprojected to the adjacent edge will produce a high density ofillumination on said screen.

Referring to Fig. '8, in which the location is aslso Iassumed to 'be inahorizontal plane, and also va. slight distance below ythat illustratedin Fig. .7, all Vtheselected-fractional beams of projected light arerefracted to crossv each other., and, .assuming further .that the lightintensity .of saidi'beams are substantially the same as those of Fior.6, the exterior bea-ms 54 and 55, will .produce .a lowdensity ofilluminated :area adjacent the edges, whereas the interior beamsl 56 and5f?, will produce a high density of illumination at the .adjacent centerlof :said screen.

It will be :apparent that a `group of low intensity 'light rays passingthrough. a low light area of a. Ciframe, and which would ordinarily bedeposited on a screen as a fixed area ofrlow illumination, is split upinto a substantially large number of beams of low intensity light whichare lprojectedonto the screen -atsubstantially uniformly spaceddistances, interposed 'between which are similar beams of light of highlintensity eminating from the light rays passing through the highlightal'efv ofthe frame.

lt is to be understood 'that the fractional beams'of projected light 46to '57 inclusive, are only a portion ofallf the light rays in the4particular plane referred to, and that ythe aforesaid refr-.actionsoccur in all the sub divided areas in verticales well as .horizontalplanes, `the preferred objectfat any one inetant,` being to .producesubstantially a checker vboardeffect as the image projected on saidscreen, the squares, orother shaped areas of -which will be so small,-thatfconsidering the rapidity with lwhich they are transposed inlocation, the effect upon afspectators eyes will be that of viewing ani-mageless surface having adensity `of illuminatienper unit area equalto the average density vof illumination of the previous scene on saidfilm, and which wasnot interceptedv by the applicants improved shutterduring the regular .period of exposure. l

lVhereas it is preferred Vtoemploy aclear, or transparent lmaterial forthe `shutter blades, as 17, I have found that translucent materials mayalso be effectively employed, and that certain shades of opalescent andiridescent materials may be employed without the use Aof pris-maticsurfaces, and that suoli shutter blades are a substantial im- Ymaterial, this loss is compensated for -by the additional lightprojected -through the yarea formingthe 'bar of space between each.frame, or sceneon the film as said bar passes'through the projected-light area when movement of the Iilm takes place, suchA movementoccurring when the `shutter blade as 17-,is interposed in -thefsaidprojected beam.

Referring to Figs. 9,' 10 and lil., Fig.. 9,

represents-a substantially enlarged section of i a selected portion ofthe shutter 17, the prism-s 58 .and 58a, of which are exaggerated as tosize and angularity for the .purpose of illustration. These prisms are.preferably -arranged in rows, the rows of one face being arrangedpreferably at, right angles, though not necessarily so, to the oppositeface, forming substantiallya checker board effect. I'f desired, prisms,as .i9 and 59a of Fig. 10, or convex lens surfaces asGO, of Fig. 11, maybe employed. n Referring to Figs. 1- and 2under ordinary operation ofthe l shutter, the projections 1Q-1Q register with the recesses 13-18.Should for any reason, the shaft supporting said shutter be stoppedabruptly while operating at ordinary speed, the inertia of the rotatingparts supported by the shutter snpport 7, will cause said support torotate with vrespect to liu-b l, thereby forcing projections lQ-lQ ontof engagement with recesses 153-43, and friction plate 11 will move tothe right. Due to the high rotative speed of said support and itsdependingparts, projections 12?-12 will be restrained from fullyentering said recesses, however, slight entry will take place actingas'abrake -to stop said rotation. Afterrotation has been reduced apredetermined amount, saidgprojections will positively seat in saidrecesses and prevent further rotation of said support on said hub.

Whereas the projections 12-12 and recesses 155-13, are shown as threeeach in number, they may be reduced to two each in number, and arrangedin a diametrical plane, in this manner insuring that the blades 1717would always be stopped at the correct circumferential location forintercepting the projected beam of light at the proper time.

The projections 6-6 act to reduce the friction between shut-ter support7 and hub 1 during the periods that projections 12-12 are dis-engagedfrom recesses 13 123, wliereby said projections are assured of enteringsaid recesses before rotation ceases even though said rotation may besubstantially slow.

It is obvious that if desired the projections 1Q-12 may be made part ofthe support 7, and the recesses 13--13 may be carried by the frictionplate 11. Also that the projections 6-6, may be made a part of saidsupport and. omitted from the flange 5.

What I claim is 1. A shutter for motion picture projectors comprising,obscuration blades formed of ransparent material, a series of linealparallelly disposed prisms formed on one face thereof, a series ofsimilarly formed prisms formed on the opposite face of the blades, therows of prisms being angularly disposed lineally with respect to therows of prisms of the first named face, the faces of the j 1isms of bothfaces having al comparatively small angle of incidence with respect tothe plane of travel of the blades, and a hub member for supporting theblades to form the shutter.

2. A shutter for motion picture projectors comprising, a hub member, aflange portion formed thereon, a flange member supported by the hubmember arranged to have co-aXial movement thereon but constrained torotate therewith, a shutter blade supporting member supportedby the hubmember positioned between the flange portion and the flange member, andresilient means supported by the hub member for restraining axialmovement of the flange member whereby the shutter blade supportingmember is clampably allocated between the flange portion and the flangemember.

3. A shutter for motion picture projectors comprising, a hub member, aflange portion formed thereon, a flange member supported by the hubmember arranged to have co-aXial movement thereon but constrained torotate therewith, a shutter blade supporting member supported by the hubmember positioned `between the rflange portion and the flange member,resilient means supported bythe hub member for restraining axialmovement of the flange member whereby the shutterblade supporting memberis clampably allocated between the flange portion and the flange member,and registering means correlatively supported by the flange member andthe shutter blade supporting member for frictional-- ly permittingrotation of the shutter blade supporting member with respect to the hubmember arranged to registeringly allocate the members in predeterminedrelative radial planes.

4. In combination with a motion picture projector for projecting motionpictures onto a screen, of a motion pictureshutter comprising,obscuration blades for-medV of'transparent material, a series oflinealparallelly disposed prisms formed on one face thereof, a series ofsimilarly formed prisms formed on theopposite face of the blades, thelast named rows of prisms being angular-ly disposed with respect to therows of thelirst named prisms, the faces of the prisms of both the'faces hav'- ing a comparatively small angle ofincidence with respect tothe plane-of travel of the blades whereby the beams of light refractedby the prisms will be mal-pictorially projected onto the screensubstantially within the frames margins of the normally projected motionpicture frames.

5. A shutter for motion picture projectors comprising, obscurationblades formed of transparent material, a plurality of rows of linealprisms formed onone fa'cethereof a'rranged to refralet the lightbeamprojected by the projector, a plurality 'of similarrows of prisms formedon theopposite face, the rows of one face being'positioned substantial"-ly at right angles to the rows of the opposite face, the angle ofincidence of the'facesf of the prisms being comparatively small withrespect to the plane of travel of the' blades, and a hub member arrangedto support 'the blades to form the shutter.

6. A motion picture shutter comprising, -a hub member arranged to besecured to'a project-or shaft for rotatively supporting the shutter, ashutter member having an annular portion surrounding a'centrallydisposed orifice` therein, frictional faces formed thereon, frictionalfaces formed on the hubmember frictionally engaging-the frictionalfacesof the shutter member for frictionally rotatively supporting theshutter member vby the hub member, the frictionalfaces ofthe shuttermember and hub member having a comparatively small frictional resistanceone to the other, mating portions formed on the frictional faces of thehub andshutter'members for frictionally allocating the shutter memberpredeterminately vradially with respect to the hub member, thefriction'al resistance of the mating portions being comparatively Vhub.member, a shutter member frictionally c supported thereby havingobscuration blades arranged to cut off the light beam of the project-orat predetermined intervals, and frictional arresting means mutuallyassociated with the members arranged to frictionally varrest therotationof the shutter member on the `hub member at predetermined relativeradial planes thereof whereby upon inadvertent frictional rotation ofthe shutter member relatively to the hub member the shutter member willbe arrested to normally cut off the light beam projected by theprojector.

8.. A motion picture shutter comprising, a hub member having an annularportion formed with a flat frictional face, and an annular memberslidably supported by the hub member having a flat frictional faceformed thereon facing thefrictional face of the lhub member, a shuttermember having an annular portion surrounding a centrally disposedorifice the annular portion having flat frictional faces arranged to befrictionally engaged between the faces of the hub and annular memberforY frictionally rotatively supporting the shutter member on thc hubmember, and frictionally engaged mating portions formed on certain ofthe frictional faces arranged to arrest the relative rotation of the huband shutter members at predetermined relative radial planes thereof. Y Y

9. ,A motion picture shutter comprising', a hub member arranged to besecured to a projector shaft for rotatively supporting the shutter, anannular port-ion formed adjacent onev end thereof having a frictionalface formed inwardly thereof, an annular member slidably supported bythehub member having a frictional face formed thereon facing the frictionalface formed on the annular portion of the hub member.v a shutter memberhaving an annular portion formed thereon surrounding a centrallydisposed orifice,the annular' portion being positioned between theannular portion of the hub member and the annular member, frictionalfaces formed on the annular portion of the shut- `ter member arranged tofrictionally engage the frictional faces of the hub and annular members,frictional mating arresting portions formed on certain of the relativelyrotat-able frictional faces arranged to frictionally arrest the'relativerotation of the hub and shutter members at predetermined radial planesthereof, and means resiliently constraining the annular memberl intofrictional engagement with the annular portion of the shutter member.

Signed at New York City, in the county of New York and State of NewYork, this 17th day of February, A. D. 1926.

' OSCAR A. ROSS.

